Interactions of Antiretroviral Drugs

The rapid expansion of antiretroviral agents in recent years has resulted in a growing potential for drug interactions, either between themselves or with other pharmacologically active compounds commonly used in the management of HIV complications. All protease inhibitors and non-nucleoside reverse transcriptase inhibitors are metabolized by cytochrome P450. At the same time, these drugs have enzyme inducing or inhibiting properties, which explains the high risk of drug interactions that their use proposes. Some of these interactions may lead to undesirable outcomes, such as severe adverse effects or sub-therapeutic drug concentrations which increase the risk of antiretroviral resistance. However, not all is negative; the prior knowledge of antiretroviral interactions can be used for the design of new regimens, optimizing doses or drug intervals in order to ensure adequate drug concentrations, or to obtain synergetic effects. Antiretroviral interactions can be classified in three main groups: Those that require a change in drug dosage, contraindicated combinations, and interactions in which special monitoring is advisable. Comprehensive tables of clinically relevant antiretroviral interactions are provided.